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Thursday, 3 May 2012

First blind patient in UK has electronic retina implanted

EngineerbloggerMay 3, 2012

Chris James has become the first person in the UK to have an electronic retina implanted into the back of his eye.

The operation took place at the Oxford University Hospitals NHS Trust with the surgical team led by Robert MacLaren, professor of ophthalmology at the University of Oxford. Professor MacLaren was assisted by Mr Tim Jackson, a consultant ophthalmic surgeon at King's College Hospital in London.

The following week, a second patient – Robin Millar, a 60 year old music producer from London – received a retinal implant at King’s College Hospital, with Professor MacLaren assisting Mr Jackson.

Both patients were able to detect light immediately after the electronic retinas were switched on, and are now beginning to experience some restoration of useful vision. Further operations are now planned for other suitable patients.

The retinal implants have been developed by Retina Implant of Germany to restore some sight to people with retinitis pigmentosa, an inherited condition that affects around one in every 3,000-4,000 people in Europe.

Retinitis pigmentosa is a progressive disease that sees light-detecting cells in the retina deteriorate over time.

Retina Implant’s devices are designed to replace the lost cells in the retina. Patients have a small microchip containing 1,500 tiny electronic light detectors implanted below the retina. The optic nerve is able to pick up electronic signals from the microchip and patients can begin to regain some sight once more.

Professor MacLaren explains: ‘What makes this unique is that all functions of the retina are integrated into the chip. It has 1,500 light sensing diodes and small electrodes that stimulate the overlying nerves to create a pixellated image. Apart from a hearing aid-like device behind the ear, you would not know a patient had one implanted.’

Chris James, 54, a council worker from Wiltshire, first began to experience night blindness in his mid-20s and was diagnosed with retinitis pigmentosa following a referral to Oxford Eye Hospital.

For a number of years, Chris’s vision remained relatively stable. But in 1990, a large dip in his vision left him legally blind. In 2003, another decrease in vision rendered Chris completely blind in his left eye and only able to distinguish lights in his right.

Chris said: ‘Initially, I did wonder why this was happening to me and I struggled a bit as the diagnosis sunk in. For a while there, we weren’t sure how badly my vision would progress so I just had to be prepared for the worst. It’s something you have to come to terms with and make the best of what you’ve got.’

Chris added: ‘After learning more about the research and the technology, I knew I wanted to get involved. Even if I didn’t stand to gain much from this, I liked the idea of contributing to future research and generations. I guess also I have nothing to lose in all of this.’

After having the artificial retina implanted in his left eye, Chris can now recognise a plate on a table and other basic shapes. And his vision is continuing to improve as he learns to use the electronic chip in an eye that has been completely blind for over a decade.

The operation took eight hours and first required implantation of the power supply which is buried under the skin behind the ear, similar to a cochlear implant. This part of the operation was performed by Mr James Ramsden of Oxford University Hospitals assisted by Mr Markus Groppe, an academic clinical lecturer at the University of Oxford.

The electronic retina was then inserted into the back of the eye and stitched into position before being connected to the power supply.

Three weeks after the operation, Chris’ electronic retina was switched on for the first time. After some initial tuning and testing, Chris was able to distinguish light against a black background.

‘As soon as I had this flash in my eye, this confirmed that my optic nerves are functioning properly which is a really promising sign,’ Chris said. ‘It was like someone taking a photo with a flashbulb, a pulsating light, I recognised it instantly.’

Chris continues to have monthly follow-up testing of his microchip. In the meantime, he is testing the microchip at home. ‘It’s obviously early days but it’s encouraging that I am already able to detect light where previously this would have not been possible for me. I’m still getting used to the feedback the chip provides and it will take some time to make sense of this. Most of all, I’m really excited to be part of this research.’

Professor MacLaren says: ‘We are all delighted with these initial results. The vision is different to normal ... and it requires a different type of brain processing. We hope, however, that the electronic chips will provide independence for many people who are blind from retinitis pigmentosa.’

Retina Implant’s technology has been in clinical trials for more than six years. Results from the company’s first human trial were published in Proceedings of the Royal Society B in November 2010 and showed patients could recognise foreign objects and read letters to form words.

A second clinical trial began in Germany in May 2010. The trial was expanded to other centres in late 2011, and now includes the UK trial at Oxford and King’s College Hospital as well as two additional sites in Germany and a site in China.

Data from nine patients implanted in Germany as part of the current trial indicate the best visual acuity to-date, with the majority of patients experiencing restoration of useful vision in daily life.

Dr Walter-G Wrobel of Retina Implant says: ‘The Oxford Eye Hospital and King’s College Hospital teams have done an excellent job and achieved exciting results. We look forward to continuing the momentum achieved in the trial thus far and to submitting for commercial approval when this phase of research is completed.’

Professor MacLaren suggests: ‘If successful, this trial may lead to establishing the electronic retina as a standard treatment for patients with retinitis pigmentosa.

‘The device is not suitable at present for age-related macular degeneration,’ he adds, ‘but advanced cases may benefit from it in future. It is not suitable for diseases that affect the optic nerve, such as glaucoma.’

The UK part of the trial is co-ordinated by Oxford University and will see up to 12 blind patients receive the implant in operations at the Oxford University Hospitals NHS Trust and King’s College Hospital in London. The UK trial is funded by a grant from the National Institute of Health Research with extra support from the Oxford Biomedical Research Centre.